Implement-carrying linkages for excavators and other similar machines can include multiple load bearing structures, such as components commonly referred to as a “boom” and a “stick,” which are fabricated from a number of steel plates joined together by welds to form a box beam (also referred to as a box section). The box beam includes a hollow region enclosed by the steel plates. The box beam structure can be subjected to significant torsional loads during use of the machine, which can deform the box beam structure and lead to failure of the component.
One solution to provide enhanced rigidity to a box beam structure subject to torsional loads is to weld baffle plates within the box beam at various locations. However, manufacturing a box beam structure having such internally-welded baffle plates requires a significant amount of tooling, welding equipment, and process time. Additionally, because the baffle plates are internal to the structure, visual inspection of the baffle plate welds requires cutting into the box beam to access the baffle plates and their associated welds, and, if warranted, repairing the box beam through the access hole.
Typical booms in the industry have a similar arrangement at the boom “nose” the portion of the boom providing a junction between the stick and the boom. Typically, two lateral members extend from the main boom body and around the stick, like a fork. Under load however, these lateral members tend to have large stress concentrations at their junction with the main body of the boom. To reduce this stress, a third member spanning between the lateral members is usually provided as an internal baffle, with internal welds that can fail without warning as they cannot be routinely inspected for early cracks. The entire nose can be a casting with the third member an integral part of the casting, but this approach can be expensive.
U.S. Patent Application Publication No. US 2013/0058748 is entitled, “Apparatus and Method for Reinforcement of a Load Bearing Structure,” and is directed to a reinforcement device for a load bearing structure. The reinforcement device may include a tubular wall including a first end, a second end, a throat disposed between the first end and the second end, and a curved portion disposed between the throat and each of the first end and the second end. The tubular wall may also include a first dimension at the throat and a second dimension at each of the first and second ends, the first dimension being smaller than the second dimension. The reinforcement device can be used as a transverse member of a component (e.g., a boom) in a linkage assembly for an excavator.
It will be appreciated that this background description has been created by the inventors to aid the reader, and is not to be taken as an indication that any of the indicated problems were themselves appreciated in the art. While the described principles can, in some respects and embodiments, alleviate the problems inherent in other systems, it will be appreciated that the scope of the protected innovation is defined by the attached claims, and not by the ability of any disclosed feature to solve any specific problem noted herein.